1. Field of the Invention
The present invention relates to energy absorbing systems, and particularly to a modular wall system which can be installed on existing concrete barrier walls in order to absorb the energy from a vehicular impact.
2. Description of Related Art
There are a number of injuries and fatalities every year due to collisions between vehicles and concrete barrier walls. This problem is especially prevalent in racing situations where drivers can reach speeds in excess of two hundred miles per hour and tracks are completely surrounded by concrete barrier walls. Concrete barriers walls are effective in keeping vehicles on the track, but impacts with these barriers can cause serious injuries or death to the drivers of the impacting vehicles due to the unyielding nature of concrete. Many of these injuries could be avoided if more impact energy was absorbed by the barrier wall rather than the occupants of the vehicle. It is therefore desirable to have an effective energy absorption system which is cost effective and easy to install on existing concrete barrier walls.
There have been a variety of systems proposed to reduce injuries to drivers when vehicles accidentally impact concrete barriers. One system is the PEDS barrier which employs high density polyethylene barrels connected to the concrete barriers with longitudinally spaced cables extending around the barrels. The barrels themselves are wrapped in a overlapping sheet of high density polyethylene material which is attached to the barrels by bolts. This system is effective in reducing injuries and absorbing energy but it is costly to install, difficult to repair and does not use air as an energy absorption means.
U.S. Pat. No. 6,276,667 discloses an energy dissipating system which is attachable to concrete barriers. This system consists of a horizontally extending flexible sheet of plastic secured to the barrier so as to form a cavity between the barrier and the plastic sheet. Inside this cavity is an elongated energy dissipating member extending horizontally within the cavity. This system is designed to reduce friction between vehicles and the barrier, but it is not designed to absorb the energy of a head-on collision at racing speeds. This system also does not have a slide-on, slide-off design, and does not use air as an energy absorption means.
U.S. Pat. No. 6,010,275 discloses an impact attenuating guard rail and includes a rail extending horizontally, a plurality of fixed support posts and a resilient, compressible, energy absorbing means mounted between the rail and the posts. This is an effective energy absorbing system but the guard rail does not use air as a means for dissipating crash energy, nor does it easily attach to an existing concrete barrier wall.
U.S. Pat. No. 5,314,261 discloses a vehicle crash cushion which includes an array of panels positioned to overlap one another and which is oriented parallel to a barrier adjacent to a roadway. Located between the panels and the barrier are elastomeric tubes which function to absorb energy when the panels are depressed toward the barrier. This system differs from the present invention in that it does not use air to dissipate crash energy. It also lacks a slidable connection to a concrete barrier wall for easy installation and repair, and it is not designed to reduce debris associated with impact. The elastomeric tubes are open at top and bottom so that they collapse readily against the barrier wall, whereas the present invention uses a unitary, enclosed core with restricted orifices venting to the atmosphere, so that considerably more force is required to compress the core of the present invention. The elastomeric tubes described in Stephens are bolted to each other, requiring considerable labor to assemble, and are secured to the concrete barrier by bolting only a single tube to the barrier. Further, the front panel is made from plywood wrapped by fiberglass, so that the plywood is prone to fracture on high speed impact. The front panel is secured to the concrete panel by a complex suspension cable structure, and apparently is not attached to the elastomeric tubes.
There is a need for an improved energy absorbing system, which is easier to install and replace, does not retain water after a rain storm which might otherwise cause a dangerous track condition, uses air as an energy absorbing means, and is designed to repeatedly absorb an impact and contribute little if any debris to the race track.
None of the above inventions and patents, taken either singly or in combination, is seen to describe the instant invention as claimed.